He was also at 1/2 HP, so no, not 18. More like 4, I think.
However, I forgot about hardness, so he may have survived. Um.
In that case, could I revise my action?
I could use Craft Action to move instead of my Haste, then I'd have two attacks at the barricade. It'd mean I couldn't try to Hide there, but that's a small price to pay for leaving an enemy alive right next to me.